Fuel pressure regulator

ABSTRACT

A fuel pressure regulator with a flexible diaphragm defining in part first and second chambers in a housing and moving a ball valve in the first chamber to open and closed positions to regulate pressure of fuel discharged from the first chamber through an outlet having a seat on which the ball is received when the valve is closed. A cage carried by the diaphragm cooperates with a carrier member or disc fixed to the ball to provide a lost motion coupling between the diaphragm and the ball valve. This coupling permits movement within predetermined limits of the diaphragm generally axially, radially and pivotally relative to the ball while it remains on its seat and upon further generally axial movement of the diaphragm opens and partially closes the ball valve to regulate and maintain substantially constant the pressure of fuel discharged from the chamber over substantially the full range of the rate at which the fuel is discharged. Preferably, to further improve regulation, a restricted orifice is disposed in the outlet downstream of the valve seat.

REFERENCE TO CO-PENDING APPLICATION

This is a continuation-in-part application of Ser. No. 07/892,252 filedJun. 2, 1992 now U.S. Pat. No. 5,220,941, and a continuation-in-part ofapplication Ser. No. 07/949,974 filed Sep. 24, 1992.

FIELD OF THE INVENTION

This invention relates to pressure regulators and more particularly to apressure regulator for liquid fuel for an internal combustion engine.

BACKGROUND OF THE INVENTION

In many engines with fuel injection systems, it is desirable to supplyliquid fuel to the injector or injectors at a pressure which varies sothat it is constant relative to the intake manifold pressure of thecombustion air. Both the combustion air pressure and the flow rate offuel supplied to the engine varies with engine speed, load and otheroperating conditions.

Previously, a variety of fuel pressure regulators have been developedone of which is shown in U.S. Pat. No. 4,627,463. This regulator has agenerally flat, flexible diaphragm disposed between two chambers andsubjected to manifold pressure on one side and pressurized liquid fuelon the other side. The flow of fuel through an outlet from the fuelchamber is controlled by a valve assembly having a ball trapped in acage carried by the diaphragm and yieldably urged by a compressionspring received in the manifold pressure chamber into engagement with aseat encircling the outlet. The ball is retained in the cage so that itcan shift slightly only laterally in a plane parallel to the diaphragm.

In use, these regulators do not achieve or maintain a uniform andconstant differential fuel pressure. Rather, the differential fuelpressure varies with the rate of fuel flow and drops as fuel consumptionincreases. Furthermore, these prior devices have a significant delay intheir response to rapid changes in intake manifold pressure and flowrate produced by rapid changes in engine load, demand or other operatingconditions. At best, transient variations of the nominal output pressureof these prior regulators have been about three to four psi.

SUMMARY OF THE INVENTION

A regulator providing substantially constant fuel pressure throughoutits normal operating range with its control valve having a lost motioncoupling with the diaphragm so that the diaphragm can shift withinpredetermined limits axially, laterally or radially and pivotally withrespect to the valve ball while it remains on its valve seat.Preferably, to improve the responsiveness of the regulator, the outletthrough which the fuel flows around the ball, has a restricted orificeconfigured to produce a force on the ball as the rate of flow increaseswhich tends to offset the increase in force on the ball produced by thespring biasing the diaphragm as the valve opens.

Preferably, to provide an improved system for controlling the cycling ofa fuel pump, a pulse width modulated (PWM) control circuit includes aswitch actuated by opening and closing of the valve in the pressureregulator to control the output of the pump supplying fuel to theregulator.

Objects, features and advantages of this invention include providing adiaphragm fuel pressure regulator which has improved regulation of theoutput pressure, a substantially constant differential output pressureover its normal operating range of variations in flow rate,substantially improved responsiveness to changes in the output flow rateand variation in fluid pressure applied to the non-fuel side of thediaphragm, and is of simplified design, economical manufacture andassembly, has a long in-service useful life, and requires no service ormaintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of this invention willbe apparent from the following detailed description, appended claims andaccompanying drawing in which:

FIG. 1 is a sectional view of a fuel pressure regulator embodying thisinvention with the ball of its control valve shown in its seated orfully closed position;

FIG. 1A is a sectional view of the pressure regulator of FIG. 1 with itsdiaphragm shown in a skewed or pivotal position relative to thelongitudinal axis of the regulator and its position illustrated in FIG.1;

FIG. 2 is a full sectional view of a modified form of the regulator ofFIG. 1.

FIG. 3 is a sectional view of a modified fuel prssure regulatorembodying this invention with the ball of its control valve shown in itsseated or fully closed position, and an electric switch shown in itsclosed or conductive position;

FIG. 4 is a semi-schematic showing of the regulator of FIG. 3 in a fuelsupply and control system for a fuel injected internal combustionengine; and

FIG. 5 is a functional block diagram of the pump control electronics ofFIG. 4.

DETAILED DESCRIPTION

Referring in more detail to the drawings, FIGS. 1 and 1A illustrate afuel regulator 10 embodying this invention having a valve assembly 12actuated by a diaphragm 14 and both received in a housing 16 defined bya body 18 and a cap 20. The diaphragm and housing define a liquid fuelfirst chamber 22 on one side of the diaphragm and a fluid second chamber24 on the other side of the diaphragm. The cap has a passage or tube 26communicating with the fluid chamber and is secured by a flange 28 witha return bend 30 rolled around the body 18 during assembly of thecomponents.

The diaphragm 14 has a relatively thin and flexible central portion 32and a circumferentially continuous peripheral rib 34 received in agroove 36 in the body and retained therein by the cap to provide a fluidtight seal between them and the diaphragm. Preferably, to provide a moreflexible and responsive diaphragm, it has a circumferentially continuouspleat or bellows 38 therein which also readily accommodates substantialaxial, radial, and pivotal displacement or movement of the diaphragm.Preferably, the diaphragm is made of a flexible elastomer such as afluorosilicone rubber or preferably an acronytrile butadiene rubber andmay be reinforced with a fabric embedded in the elastomer.

Liquid fuel is admitted to the chamber 22 through an annular recess 39and circumferentially spaced inlet ports 40 in the body. When the valveassembly 12 opens, liquid fuel is discharged from the chamber through anoutlet passage 42 in the body. The valve assembly 12 has a sphericalcheck ball 44 which bears on a spherical seat 46 in a sleeve 48 receivedor pressed into a counterbore 50 in the outlet passage 42 to prevent thedischarge of fuel while the valve assembly is closed.

As illustrated by comparison of FIGS. 1 and 1A, it has been discoveredthat when pressurized fuel in the chamber moves the diaphragm 14, itsmovement is inconsistent and varies from one time to the next and inmass produced regulators from one regulator to the next. The motion ofthe diaphragm varies axially and laterally, radially or in a planegenerally perpendicular to the longitudinal axis 52 of the regulator.The motion also varies the angle of orientation by tilting, skewing,rocking or wobbling the diaphragm so that the plane of the diaphragm isnot perpendicular to the longitudinal axis. In prior art regulators,this inconsistent movement of the diaphragm adversely affected theperformance of the regulator by producing variations in the lift-off andseating of the ball or other valve closure member which contributed tovariations in the output pressure as the quantity of fuel flowingthrough the chamber varies.

In accordance with this invention, these problems are obviated by a lostmotion coupling of the diaphragm with the ball which permits thediaphragm to move axially, radially, and pivotally relative to the balland to rotate the ball on its valve seat wherever necessary before beinglifted off the seat by the diaphragm to open the valve assembly. Thiscoupling is accomplished by the cooperation of a central flange or disc54 loosely received in a cage 56. The disc 54 is fixed to the ball 44and the cage 56 is attached to the diaphragm for movement therewith.Preferably, the disc has a slightly undersized central hole and is pressfit onto the ball so they move together in unison. The cage has ahat-shaped housing 58 with a crown having a top 60 and a cylindricalside wall 62 and a circumferentially continuous brim or flange 64 with adownturned edge 66 over which an upturned edge 70 of a retainer ring 72is press fit to loosely entrap the disc in the cage.

The retainer ring 72 has a clearance hole 74 large enough so that theball will not bear on the ring when the cage shifts off center relativeto the seated ball sufficiently so that the cage bears on the side wall76 of the chamber 22. Preferably, the inside diameter of the brim edge66 of the cage is sufficiently greater than the outside diameter of thedisc 54 so that when the cage is shifted radially sufficientlyoff-center relative to the seated ball, the cage will strike the wall 76of the chamber without contacting the periphery of the disc which woulddisplace the ball from its seat.

Preferably, the longitudinal or axial distance between the inner facesof the brim of the cage 56 is sufficiently greater than the thickness ofthe disc 54 so that, as shown in FIG. 1A, a skewing, rocking, pivotal ororbital motion of the diaphragm and cage will not displace the ball 44when received on its valve seat 46 and at most will contact oppositesides of the disc 54 in generally diametrically opposed locations androtate the ball while it remains on the valve seat so that the disc isparallel to the brim of the cage.

The crown 62 of the cage projects through a central hole in thediaphragm which is secured and sealed to the cage by a retainer ring 78with an upturned edge and a central hole which in assembly is press fitover the crown and bears on the diaphragm to seal it to the brim flange64. The diaphragm and cage are yieldably biased toward the valve seat 46by a compression spring 80 disposed in the chamber 24 and bearing on theretainer ring and cap. The spring is retained generally in co-axialalignment with the longitudinal axis 52 by an annular shoulder 82 in thecap on which it seats and the cage is generally co-axially aligned withthe spring by the upturned edge of the retainer ring 78.

In accordance with another feature of this invention, the ball 44 anddisc are yieldably biased toward the open end of the cage by a separaterelatively small and light weight compression spring 84 received betweenthe ball and the top 60 of the cage. This reduces the increased forceapplied to the ball due to the opening of the valve or unseating of theball because this spring 84 has a substantially smaller spring rate andtotal force than the substantially larger spring 80 biasing thediaphragm.

This spring 84 also insures that when the valve is closed initialmovement radially, axially and pivotally of the diaphragm and cage willnot unseat the ball and at most will merely rotate it so that the discis parallel to and bears on the retainer ring when the ball is initiallylifted from the valve seat. This spring 84 also insures that when thevalve is open the ball 44 and disc 78 will be in a stable position withthe lower face of the disc bearing on the retainer ring 72, the initialclosing of the valve will be stable because the ball will seat or closewhen it first contacts the seat 46 even though the diaphragm and cagemay continue to move, axially, radially and orbitally thereafter, andrepeated opening and closing of the valve will be stable and repeatable.

In accordance with this invention to provide improved pressureregulation and responsiveness, preferably, but not necessarily, when thevalve is opened the increased force acting on the ball 44 due to axialdisplacement of the diaphragm spring 80 by the fuel to lift the ball offthe seat is at least partially offset or balanced by an opposing forceacting on the ball and produced by a restricted orifice 86 disposed inthe outlet. To create this counter force, the minimum cross sectionalarea of the orifice or venturi 86 is substantially smaller than thecross section area of the valve seat 46 or opening through which fuelflows. For any specific regulator construction, the desired minimumcross sectional area of the orifice can be calculated and is in part afunction of the spring rate of the diaphragm spring 80 and the axialextent to which the ball is displaced from its seat when the valve isopened sufficiently to accommodate the maximum flow rate of the fuel.This area can also be determined impirically. Typically, the minimumcross sectional area of the throat of the venturi 86 is about 1/10 to1/2 and usually 1/5 to 4/10 of the cross sectional area of the valveseat 46.

Depending on the particular engine fuel injection and control systemwith which the regulator is used, the fluid chamber 24 communicatesthrough the tube 26 with one of the atmosphere to compensate for varyingatmospheric conditions under which the engine operates, the combustionair intake manifold to provide a substantially constant differentialfuel pressure for supplying liquid fuel to fuel injectors or the like,or to a source of compressed air or other gas to vary and control thepressure under which liquid fuel is supplied to the fuel injectors inresponse to varying engine demand, load and other operating conditions.

In some fuel systems, conditions may occur where the gas pressure in thefluid chamber 24 exceeds the pressure of the fuel or fluid in the fuelchamber 22 sufficiently that after the valve 12 closes, the bellows 38or pleated area of the diaphragm 14 is forced toward the fuel chamberand tries to invert and collapse into the fuel chamber. For example, insome fuel systems under some conditions the pressure applied to thefluid chamber 24 it could be 80 psig and the pressure in the fuelchamber 22 could be reduced to atmospheric pressure. In accordance withthis invention, preferably, but not necessarily, this inversion of thebellows 38 or pleated area of the diaphragm is prevented by the locationand contour of an annular wall portion 88 of the body which limits theextent to which the pleated portion of the diaphragm can be displacedtoward the fuel chamber to prevent inversion of the pleated portion.This wall portion 88 generally underlies the bellows 38 and in normaloperation is spaced from the bellows. However, if the differentialpressure acting on the disphragm forces the bellows generally axiallytoward the seat, the bellows bears on the wall portion 88 which therebylimits its axial movement to prevent inversion of the bellows. If thepleated portion 38 were repeatedly inverted and forced into the fuelchamber, the diaphragm could be damaged which would substantiallyshorten its useful life.

FIG. 2 illustrates a modified fuel regulator 90 in which all of thecomponents identical to those of the fuel regulator of FIGS. 1 and 1Ahave the same reference numerals. This regulator 90 has a modified valveassembly 12' in which a semi-spherical ball 92 is fixed to one side of adisc 94 received in the cage 56. Both faces of the disc aresubstantially flat or planar and parallel to each other. The cage has amodified housing 58 with a smaller diameter tubular wall 98 in which atube shaped plunger 100 with a flat closed end is slidably received withits closed end yieldably biased into engagement with the upper flat face96 of the disc by a compression spring 104 received in the plunger.

In accordance with another feature of this invention, preferably thegenerally axial movement of the ball and disc in the cage is dampened bythe spring 104 and plunger 100 assembly. In use, with liquid fuel in theplunger from the chamber 22, the plunger 100 acts as a hydraulic damperof the generally axial movement of the ball and disc in the cage due toa relatively close sliding fit of the plunger in the crown 98 of thecage. If desired, the plunger and hydraulic damper arrangement can alsobe used with the spherical check ball 44 and disc 54 of the regulator ofFIG. 1.

In use, this plunger 102 and spring 104 arrangement allows the diaphragmand cage 56 to move radially and pivotally relative to the ball 92 anddisc 94 similar to that of the regulator of FIG. 1. This spring andplunger arrangement increases the tendency, when the valve is closed, ofthe ball and disc to pivot or rock on the seat in unison with thepivotal, oribital or skewing movement of the diaphragm and cage.

Typically, the regulators 10 and 90 are installed in the fuel system foran engine by inserting the free end of the body 16 into a coupler (notshown). The coupler connects the outlet of a fuel pump to the regulatorfuel inlet 39, and the regulator outlet 42 of fuel at a regulatedpressure to a fuel distribution system of the engine such as a fueldistribution rail for a plurality of fuel injectors. Depending on thenature to the control system, the tube 26 communicating with the fluidchamber 24 is connected to communicate with one of the atmosphere, thecombustion air intake manifold or a source of compressed air.

In use, prior to energizing the fuel pump preparatory to starting theengine, the valve assembly 12 or 12' of the regulator 10 or 90 isnormally closed, by the force produced by the diaphragm spring 80. Whenthe pressure of the fuel supplied to the chamber rises sufficiently, thediaphragm 14 begins to move away from the valve seat 46 while the ball44 or 92 remains on the valve seat due to the force acting on itproduced by the ball spring 84 or 104. As the fuel pressure continues toincrease and the diaphragm continues to move away from the seat, theretainer ring 72 contacts the lower face of the disc 78 or 94 and,unless the disc is already parallel to the plane of the retainer ring,continued movement of the diaphragm and cage rotates the disc while theball remains on the seat 46 so that the disc is parallel to and engagedby the ring 72 substantially throughout its circumference, whereuponcontinued movement of the diaphragm and cage lifts the ball off theseat. Upon lift off of the ball, the fuel flows between the seat and theball and through the outlet 42 at a regulated and essentially constantpressure. The restricted orifice 86 minimizes the pressure dropresulting from the flow of fuel through the outlet 42 and creates aforce acting on the ball 44 or 92 which opposes the increase in theforce acting on the ball produced by the diaphragm spring 80 as the ballmoves farther away from the seat as the rate of flow of fuel to theoutlet increases.

As shown by comparison of FIGS. 1 and 1A, it has been discovered thatwhen the diaphragm is moved by the pressurized fuel in the chamber 22,it does not have a uniform motion or a repeatable pattern of motion fromone opening of the valve to the next. Furthermore, in mass producedregulators, the motion of the diaphragm for opening the valve variesfrom one regulator to another having the same design, construction,arrangement and nominal size. The lateral or radial shifting, and theskewing, rocking, pivoting, orbital and other non-axial movement of thediaphragm in regulators embodying this invention does not adverselyaffect the opening and closing of the valve assembly 12 or 12' or theresponsiveness of the pressure regulator. This is achieved by the lostmotion construction and arrangement of the cage, ball and disc whichoperably connects the diaphragm to the ball for opening and closing thevalve while still allowing the diaphragm to shift within predeterminedlimits radially, axially, pivotally and orbitally with respect to theball when received on the seat.

FIG. 3 illustrates a pressure regulator 10' embodying this inventionwith an electric switch 108 actuated by opening and closing of the valve12 to provide a signal for controlling operation of a fuel pump. Switch108 has a lower switch contact provided by the seat 46 of the sleeve 48'and an upper switch contact provided by the ball 44.

Preferably, the sleeve 48' has an annular flange 110 extending radiallyfrom the upper end of the sleeve and is of an electrically conductivematerial such as brass or steel. Preferably, the outer diameter offlange 110 is sufficiently large so that even if upturned edge 70 ofring 72 bears against side wall 76, the ring will still bear on theflange around their entire circumference when the cage is fully extendedby the spring 80. An electrical lead wire 116 is connected to the flange110 and hence to the lower switch contact provided by the seat 46. Theupper switch contact provided by the ball 44 is electrically connectedto a lead wire 118 through cap 20, spring 80, retainer ring 78, housing58, spring 84, and the ball 44 all of which are of an electricallyconductive material such as steel.

FIG. 4 illustrates a fuel delivery system 122 incorporating the pressureregulator 10' for an internal combustion engine 124. The fuel deliverysystem has fuel injectors 126, connected to a fuel injector rail 128, afuel tank 130, an electric fuel pump 132 (preferably within the tank),and a circuit 134 to control the speed of an electric motor 136 of thefuel pump and hence its rate of output of fuel.

The pump control electronics 134 is illustrated in greater detail inFIG. 5. The vehicle power system, illustrated by battery 140, providespower to a system voltage bus 142 that is connected to the pump motor136. A voltage regulator 144 supplies a regulated voltage from bus 142to switch 108 of regulator 10', to a buffer 146 and to a pulse widthmodulation (PWM) amplifier 148. The contacts of regulator/switch 108provide a signal input to buffer 146, which has a high impedance inputto reduce arcing and current draw through the switch contacts. Theoutput of buffer 146 is connected to one input of a summing junction150, which provides a control input to PWM amplifier 148. The output ofPWM amplifier 148 is connected to a power switch stage 152 that controlscurrent through motor 136. The junction of motor 136 and stage 152 isconnected as one input to a second summing junction 154, which alsoreceives an input from system bus 142 and a reference voltage thirdinput from a resistor 156 or the like. The output of junction 154provides the second input to junction 150.

In operation, control circuit 134 illustrated in FIG. 5 operates in thesame manner as that disclosed in the above-noted U.S. application Ser.No. 07/949,974, the disclosure of which is incorporated herein byreference. That is, regulator/switch 108 is responsive to pump outletpressure for switching between conductive and non-conductive conditionsat the preselected pump outlet pressure determined by the regulatorspring and diaphragm. Pulse width modulation amplifier 148 is controlledby regulator/switch 108 for applying pulsed d.c. energy to pump motor136 at a first average voltatge level when the pressure switch isconductive, and at a second lesser average voltage level when thepressure switch is non-conductive. In this way, electrical power isapplied to the pump motor at a reduced but non-zero level when pumpoutlet pressure exceeds the threshold level of the regulator/switch. Thesecond lesser average voltage level is proportional to the referencevoltage determined by resistor 156. The pulse width modulation amplifieris also controlled in part by system voltage, so that pump motoractivation remains substantially constant independent of minor voltagefluctuations.

In the preferred embodiment of the present invention, the frequency ofthe pulsed d.c. energy applied to pump motor 136 remains constant, whilethe duty cycle switches between a first duty cycle when pump outletpressure is below the regulator/switch threshold and a second lesser butnon-zero duty cycle when pump outlet pressure is above theregulator/switch threshold. The modulation frequency and the two dutycycles are preset in the design of PWM amplfier 148, although the samemay be made adjustable if desired. In this way, electrical energyapplied to the pump is automatically reduced when outlet fuel pressurebecomes excessive, reducing wear on the pump and heat dissipation by thepump. However, the pump continues to operate at the lesser level,eliminating potential inertial problems when higher pump output isrequired. The high input impedance of buffer 146 limits currentconducted through the contacts of regulator/switch 108 as previouslyindicated, thereby reducing pitting and arcing at the switch contacts.

Since switch 108 opens and closes in unison with the regulator valve 12,it tends to counteract or reduce the tendency of the fuel pump toovershoot and undershoot the regulated fuel pressure of the output ofthe regulator. The regulator 10' functions in essentially the samemanner as regulator 10 to regulate and control the pressure of the fueldischarged from the regulator.

Pressure regulators embodying this invention have substantially improvedresponsiveness to rapid changes in the rate of flow of fuel dischargedfrom the regulator and substantially improved regulation of the pressureof the fuel discharged from the regulator. For example, for regulatorsembodying this invention with a constant outlet fuel pressure with anominal value of 40 pounds per square inch gauge, the actual pressurevariation or drop is only about 0.5 to 0.6 psi over the full range ofvariation of the fuel flow rate from zero to 30 gallons per hour. Thisregulator was constructed in accordance with the disclosure of FIG. 1with nominal dimensions of the ball diameter of 0.281", disc diameter of0.542"and thickness of 0.060", the annular pocket of the cage in whichthe disc is received having an inside diameter of 0.602" and an axialheight of 0.100", the diaphragm compression spring producing a nominalforce of 19 pounds when the valve is closed and having a spring rate of22.3 pounds per inch, the ball spring producing a nominal force when thevalve is closed and the cage bears on the disc as shown in FIG. 1 of1.99 pounds and having a spring rate of 5.3 pounds per inch, the valveseat having a cross sectional area of 0.03167 of square inch, and theventuri having a throat with a minimun cross sectional area of 0.00418of a square inch.

What is claimed:
 1. A fuel pressure regulator comprising: a housing, adiaphragm defining in cooperation with the housing a first chamber and asecond chamber, a passage from the second chamber to the exterior of thehousing, a fuel inlet to the first chamber, a fuel outlet from the firstchamber, a valve seat associated with said fuel outlet and having agenerally circular seat surface for engagement with a complementaryvalve element, a first spring in said second chamber and urging saiddiaphragm generally axially toward said valve seat, a cage carried bysaid diaphragm, a valve element having an exterior surface portioncomplementary to and for mating sealing engagement with said circularvalve seat, said valve element being carried by said cage and movablegenerally axially by said diaphragm to a closed position received onsaid valve seat and to an open position spaced from said valve seat, anelectrical switch having a first contact of an electrically conductivematerial fixedly disposed within said first chamber, a second contact ofan electrically conductive material and movable with said diaphragm andsaid cage so that when said valve is closed said first and secondcontacts are in a conductive state, and when said valve is open saidcontacts are in a non-conductive state, and pulse width modulation meanscoupled to said switch for applying pulsed d.c. energy to an electricmotor of a fuel pump at a first frequency and duty cycle when saidswitch is in said conductive state, and at a second non-zero frequencyand/or non-zero duty cycle less than said first frequency and/or dutycycle when said switch is in said non-conductive state, such thatelectrical power applied to the pump motor is reduced when pump outletpressure applied to said regulator opens said switch.
 2. The pressureregulator set forth in claim 1 wherein said first and second frequenciesand duty cycles are preset in said pulse width modulation means.
 3. Thepressure regulator set forth in claim 2 wherein said first and secondfrequencies are identical.
 4. The pressure regulator set forth in claim2 wherein said pulse width modulation means further includes meansconnected to said switch for limiting current conducted by said switchin said conductive state of said switch.
 5. A fuel pressure regulatorcomprising: a housing, a diaphragm defining in cooperation with thehousing a first chamber and a second chamber, a passage from the secondchamber to the exterior of the housing, a fuel inlet to the firstchamber, a fuel outlet from the first chamber, a valve seat associatedwith said fuel outlet and having a generally circular seat surface forengagement with a complementary valve element, a first spring in saidsecond chamber and urging said diaphragm generally axially toward saidvalve seat, a cage carried by said diaphragm, a valve element having anexterior portion with a generally spherical surface portioncomplementary to and for mating sealing engagement with said circularvalve seat, said valve element being carried by said cage and movablegenerally axially by said diaphragm to a closed position received onsaid valve seat and to an open position spaced from said valve seat, asecond spring carried by said cage and yieldably urging said valveelement generally axially toward said valve seat relative to said cage,a carrier element carried by said valve element for movement in unisontherewith and projecting generally radially of the longitudinal axis ofsaid valve element, said valve element comprises a ball, said carrierelement comprises a disc encircling the mid portion of said ball,projecting generally radially outward thereof and fixed to said ball formovement in unison therewith, said cage having a cavity in which saidcarrier element is received, said cavity and said carrier element beingdimensioned and constructed and arranged to provide a lost motioncoupling between said diaphragm and said valve element so that with saidvalve element on said valve seat said diaphragm can move generallyaxially, rdially and pivotally within predetermined limits relative tosaid valve element without moving it from said valve seat and thereafterupon further generally axial movement of said diaphragm away from saidvalve seat said valve element will be moved from its closed positiontoward its fully open position, and an electrical switch having a firstcontact of an electrically conductive material fixedly disposed withinsaid first chamber, a second contact of an electrically conductivematerial and movable with said diaphragm and said cage so that when saidvalve is closed said first and second contacts are in a conductivestate, and pulse width modulation means coupled to said switch forapplying pulsed d.c. energy to an electric motor of a fuel pump at afirst frequency and duty cycle when said switch is in said conductivestate, and at a second non-zero frequency and/or non-zero duty cycleless than said first frequency and/or duty cycle when said switch is insaid non-conductive state, such that electrical power applied to thepump motor is reduced when pump outlet pressure applied to saidregulator opens said switch.
 6. The pressure regulator set forth inclaim 5 wherein said first and second frequencies and duty cycles arepreset in said pulse width modulation means.
 7. The pressure regulatorset forth in claim 6 wherein said first and second frequencies areidentical.
 8. The pressure regulator set forth in claim 6 wherein saidplulse width modulation means further includes means connected to saidswitch for limiting current conducted by said switch in said conductivestate of said switch.
 9. The pressure regulator of claim 5 wherein saidfirst contact is the top surface of an integral circumferential annularflange extending radially outward from said valve seat.
 10. The pressureregulator of claim 5 wherein said second contact is the bottom surfaceof said cage.
 11. The pressure regulator of claim 5 wherein said carriermember comprises a disc fixed to said valve element for movement inunison therewith and having a maximum outside diameter which is smallerthan the inside diameter of said cavity, and a generally axial thicknesswhich is less than the generally axial extent of said cavity adjacentthe perimeter of said disc.
 12. The pressure regulator of claim 5wherein said disc has a pair of generally planar faces which are spacedapart and parallel to each other, and said cavity has a pair generallyplanar faces which are generally axially spaced apart and parallel toeach other and overlap the periphery of said disc which is receivedbetween said planar faces of said cavity of said cage.
 13. The pressureregulator of claim 5 which also comprises a restricted orifice disposedin said fuel outlet downstream of said valve seat and having a minimumcross sectional area in the range of 1/10 to 1/2 of the cross sectionalarea of said valve seat.
 14. The pressure regulator of claim 5 whereinsaid flexible diaphragm has at least one circumferentially continuouspleat therein.
 15. The pressure regulator of claim 5 wherein saidflexible diaphragm has at least one circumferentially continuous pleattherein circling and disposed generally radially outwardly of said cageand said housing has in said second chamber a circumferentiallycontinuous wall portion generally axially aligned with and normallyspaced from said pleat in said diaphragm and constructed and arrangedfor said diaphragm to bear on said wall portion to prevent inversion ofsaid pleat when the pressure of fluid in said second chamber and actingon said diaphragm exceeds the pressure of any fluid in said firstchamber acting on said diaphragm.
 16. A fuel pressure regulatorcomprising: a housing, a diaphragm defining in cooperation with thehousing a first chamber and a second chamber, a passage from the secondchamber to the exterior of the housing, a fuel inlet to the firstchamber, a fuel outlet from the first chamber, a valve seat associatedwith said fuel outlet and having a generally circular seat surface forengagement with a complementary valve element, a first spring in saidsecond chamber and urging said diaphragm generally axially toward saidvalve seat, a cage carried by said diaphragm, a valve element having anexterior portion with a generally spherical surface complementary to andfor mating sealing engagement with said circular valve seat, said valveelement being carried by said cage and movable generally axially by saiddiaphragm to a closed position received on said valve seat and to anopen position spaced from said valve seat, a second spring carried bysaid cage and yieldably urging said valve element generally axiallytoward said valve seat relative to said cage, a carrier element carriedby said valve element for movement in unison therewith and projectinggenerally radially of the longitudinal axis of said valve element, saidvalve element comprises a semi-spherical body, said carrier elementcomprises a disc fixed to said semi-spherical body and projectinggenerally radially outwardly thereof for movement in unison therewith,said cage having a cavity in which said carrier element is received,said cavity and said carrier element being dimensioned and constructedand arranged to provide a lost motion coupling between said diaphragmand said valve element so that with said valve element on said valveseat said diaphragm can move generally axially, radially and pivotallywithin predetermined limits relative to said valve element withoutmoving it from said valve seat and thereafter upon further generallyaxial movement of said diaphragm away from said valve seat said valveelement will be moved from its closed position toward its fully openposition, said cage has a pocket therein communicating with said firstchamber to receive therein liquid fuel from said first chamber, and aplunger slidably received in said pocket, bearing on said valve elementand constructed and arranged to provide a hydraulic damper of generallyaxial movement of said valve element relative to said cage, said plungeris constructed and arranged so that said plunger can move generallyradially and pivotally relative to said carrier element, an electricalswitch having a first contact of an electrically conductive materialfixedly disposed within said first chamber, a second contact of anelectrically conductive material and movable with said diaphragm andsaid cage so that when said valve is closed said first and secondcontacts are in a conductive state when said valve is open said contactsare a non-conductive state, and pulse width modulation means coupled tosaid switch for applying pulsed d.c. energy to an electric motor of afuel pump at a first frequency and duty cycle when said switch is insaid conductive state, and at a second non-zero frequency and/ornon-zero duty cycle less than said first frequency and/or duty cyclewhen said switch is in said non-conductive state, such that electricalpower applied to the pump motor is reduced when pump outlet pressureapplied to said regulator opens said switch.
 17. The pressure regulatorset forth in claim 16 wherein said first and second frequencies and dutycycles are preset in said pulse width modulation means.
 18. The pressureregulator set forth in claim 17 wherein said first and secondfrequencies are identical.
 19. The pressure regulator set forth in claim17 wherein said pulse width modulation means further includes meansconnected to said switch for limiting current conducted by said switchin said conductive state of said switch.
 20. The pressure regulator ofclaim 16 wherein said second spring is disposed in said pocket andyieldably urges said plunger generally axially toward said valve elementand said valve element toward said seat relative to said cage.
 21. Thepressure regulator of claim 20 wherein said first spring produces aforce acting on said diaphragm having a greater magnitude than the forceproduced by said second spring acting on said valve element, and saidfirst spring has a higher spring rate than the spring rate of saidsecond spring.
 22. The pressure regulator of claim 5 wherein said firstspring produces a force acting on said diaphragm having a greatermagnitude than the force produced by said second spring acting on saidvalve element, and said first spring has a higher spring rate than thespring rate of said second spring.
 23. The pressure regulator of claim16 whrein said first contact is the top surface of an integralcircumferential annular flange extending radially outward from saidvalve seat.
 24. The pressure regulator of claim 16 wherein said secondcontact is the bottom surface of said cage.